Vertebral osteosynthesis equipment

ABSTRACT

This equipment includes bony anchoring members, such as pedicular screws ( 1 ) and/or hooks, one or two linking rods ( 2 ), intended to be connected to these anchoring members, and parts ( 3 ) for connecting this(these) linking rod(s) ( 2 ) to these anchoring members, at least one anchoring member including a proximal threaded stud ( 6 ) and a clamping means ( 4 ) for assembling a connecting part ( 3 ) thereon, and this connecting part ( 3 ) including a clamping means ( 5 ) for immobilising the linking rod ( 2 ) with respect thereto. According to the invention,  
     said connecting part ( 3 ) comprises a rounded section ( 20 ) intended for hugging a linking rod ( 2 ) and two parallel branches ( 21, 22 ) drilled with holes enabling engagement on the proximal threaded stud ( 6 ) of said anchoring member ( 1 ), these two branches ( 21, 22 ) being laid out for being clamped in order to clamp said rounded section ( 20 ) around the linking rod ( 2 ); and  
     said clamping means ( 4, 5 ) may be engaged coaxially on the proximal threaded stud ( 6 ) of said anchoring member ( 1 ), a first clamping means ( 4 ) enabling the assembly of the connecting part ( 3 ) on this proximal threaded stud ( 6 ) and the second clamping means ( 5 ) enabling to clamp both branches ( 21, 22 ) of this connecting part ( 3 ).

This patent application claims the priorities to:

FR 03 07778, filed on Jun. 27, 2003;

U.S. Provisional application No. 60/490,518, filed on Jul. 29, 2003.

The present invention relates to a vertebral osteosynthesis equipment.

A vertebral osteosynthesis equipment generally includes bony anchoring members, such as pedicular screws or hooks, one or two linking rods, intended to be connected to these anchoring members and to be attached to the vertebrae by dint thereof, and parts for connecting this(these) linking rod(s) to these anchoring members. The equipment may also comprise length-adjustable crossbeams, which link transversally two parallel linking rods in order to hold said rods with respect to one another.

In an existing type of equipment, each anchoring member comprises a proximal threaded stud whereon a nut may be screwed, and each connecting part comprises a rounded section intended for surrounding a linking rod and two parallel branches drilled with holes. These branches are intended for engaging onto said proximal stud and for being clamped, by means of that nut, against a bearing surface provided on the anchoring member, said operation enabling to clamp said rounded section around the linking rod and thereby ensuring longitudinal immobilisation of this rod with respect to the anchoring member. The anchoring members may be of “monoaxial” type, i.e. comprise a proximal threaded stud integral with the base portion of the anchoring member serving for bony anchoring, or may be of “polyaxial” type, i.e. comprise a proximal threaded stud articulated with respect to that base portion.

When installing the equipment, the anchoring member(s) are placed on the vertebrae, then extension pieces are engaged on the proximal studs of these anchoring members. The connecting parts, with the rod(s) engaged in their rounded portions, are then engaged on these extension pieces and run down along the latter until they rest on the anchoring members. The extension pieces are then withdrawn and the clamping nuts are placed.

To enable adequate correction of the position of the vertebrae, the linking rod(s) must be shaped in one or several planes. This operation leads to successive trials until the adequate form is obtained. Successive insertions and retractions of the extension pieces and successive running down operations of the assemblies composed of connecting parts—linking rods along the latter, then withdrawing the extension pieces for placing the nuts, are then relatively tedious and time-consuming operations.

Moreover, with polyaxial anchoring members, the movements of the proximal studs modify the positions of the connecting parts and disturb consequently the determination of the form which should be given to the linking rod(s) so that these rods may be engaged in these connecting parts, which disturbs noticeably the installation of the equipment.

It is besides known by the documents US 2003/028191 or U.S. Pat. No. 6,050,997 to provide a single-branch connecting part, with a closed housing for receiving the linking rod, fitted with a screw, this screw enabling to clamp the linking rod in this housing.

This connecting part structure is assessed as non-optimal, from the handiness viewpoint of the equipment at installation as from the viewpoint of the clamping obtained.

The purpose of the present is to remedy the shortcomings of existing equipment, by providing vertebral osteosynthesis equipment noticeably easier and quicker to be implanted than any extent equipment.

Another object of the invention is to provide a piece of equipment enabling to facilitate noticeably the determination of the form to confer to the linking rod(s).

An additional object of the invention is to provide a piece of equipment enabling perfect clamping of a linking rod, as resistance to the repeated loads inflicted to this type of equipment.

The equipment affected includes, in itself, bony anchoring members, such as pedicular screws or hooks, one or two linking rods, intended to be connected to these anchoring members and to be attached to the vertebrae by dint thereof, and parts for connecting this(these) linking rod(s) to these anchoring members, at least one anchoring member including a proximal threaded stud and a clamping means for assembling a connecting part thereon, and this connecting part including a clamping means for immobilising the linking rod with respect thereto.

According to the invention,

said connecting part comprises a rounded section intended for hugging a linking rod and two parallel branches drilled with holes enabling engagement on the proximal threaded stud of said anchoring member, these two branches being laid out for being clamped in order to clamp said rounded section around the linking rod; and

said clamping means may be engaged coaxially on the proximal threaded stud of said anchoring member, a first clamping means enabling the assembly of the connecting part on this proximal threaded stud and the second clamping means enabling to clamp both branches of this connecting part.

Both these clamping means enable to facilitate noticeably the determination of the form to confer to the linking rod(s) and to make the equipment noticeably easier and quicker to be implanted than any extent equipment, while enabling perfect clamping of a linking rod, as resistance to the repeated loads inflicted to this type of equipment.

According to an embodiment of the invention,

the proximal branch of the connecting part, i.e. the furthermost from the vertebrae after implantation, comprises a hole for letting said first clamping means therethrough, so that said first clamping means rests, when screwed on said proximal threaded stud, solely on the distal branch of the connecting part, and

said second clamping means exhibits a diameter greater than that of this hole, so that said second clamping means rests, when screwed on said proximal threaded stud, on the proximal branch of the connecting part, thereby clamping both branches and therefore immobilising the linking rod.

This connecting part may thus be clamped on the anchoring member by dint of said first clamping means without clamping the branches of the connecting part, therefore with the possibility of placing and retracting the linking rod. The connecting part may therefore be placed on the anchoring member in its final position, before the linking rod is formed as requested.

According to another embodiment of the invention,

the hole of the distal branch of the connecting part, i.e. the closest of the vertebrae after implantation, is tapered;

said second clamping means is in the form of a tubular screw, which may be screwed in the hole of the distal branch and rest against the proximal branch for clamping both branches, the axial bore of this screw having a diameter greater than that of the proximal threaded stud so as not to oppose the engagement of the connecting part, thus equipped with said second clamping means, on the proximal threaded stud, and

said first clamping means is in the form of a nut which may rest against the head of the screw formed by said second clamping means, for assembly of the connecting part on the proximal threaded stud.

The connecting part according to this embodiment may therefore be clamped on the linking rod then may be engaged on the proximal threaded stud of an anchoring member and be installed on this anchoring member.

According to still another embodiment of the invention,

the proximal branch of the connecting part is shorter than the distal branch and comprises a scalloping at of its free end;

the first and second clamping means comprise nuts which may be screwed on the proximal stud of the corresponding anchoring member,

said scalloping having dimensions greater than that the nut which is part of said first clamping means, to enable this nut to rest, when being clamped, against the distal branch and to clamp this branch against the proximal zone of the portion of the anchoring member engaged with the vertebra until the connecting part is locked with respect to said proximal stud, and said scalloping having dimensions smaller than those of the nut which is part of said seconds clamping means, to enable this nut to rest, when being clamped, against the proximal branch and to bring both branches closer to one another in order to immobilise the linking rod in said rounded section of the connecting part.

The invention will be better understood, and other characteristics and advantages thereof will appear, with reference to the appended schematic drawing, representing, for non-limiting exemplification purposes, several possible embodiments of parts included in the equipment affected.

FIG. 1 is a partial view of a polyaxial pedicular screw, of a linking rod seen from its end, of a connecting part in cross-section and of two nuts included in such equipment, according to a first embodiment;

FIG. 2 is a view of the connecting part, from above;

FIG. 3 is a view of the screw and of the connecting part similar to FIG. 1, after assembly of a first nut;

FIG. 4 is a view similar to FIG. 3, after assembly of the second nut;

FIG. 5 is a perspective view of a connecting part and of two nuts according to a second embodiment;

FIG. 6 is a sectional view thereof, as they are placed on an anchoring member;

FIG. 7 is a perspective view of a connecting part, of a nut and of a screw according to a third embodiment;

FIG. 8 is a sectional view of this connecting part and of this screw, and

FIG. 9 is a partial view of a polyaxial pedicular screw, of a connecting part in cross-section and of two nuts included in such equipment, according to a third embodiment.

The portions or elements of an embodiment which can be found identically or similarly in another embodiment will be designated, in the following description, by the same numeric references.

FIG. 1 represents a polyaxial pedicular screw 1, a rod 2 connecting several of these screws 1, a part 3 connecting this rod 2 to one of these screws 1 and two nuts 4, 5 enabling to assemble the linking rod 2 to this screw 1.

The screw 1 comprises a proximal threaded stud 6 and threaded distal screw body 7. The stud 6 is intended for receiving the part 3 engaged thereon and the nuts 4, 5 screwed thereon while the body 7 is intended for insertion into the pedicula of a vertebra.

The stud 6 exhibits a threaded cylindrical portion 10, a spherical distal head 11 and a threaded proximal rod 12.

The portion 10 exhibits a zone 15 of reduced diameter, enabling to break its proximal portion after placing and clamping nuts 4, 5, as appears by comparison of FIGS. 3 and 4.

The head 11 is intended for engaging into a proximal cavity 16 delineated by the proximal zone of the body 7 and for retention in this cavity by crimping a proximal wall 17 exhibited by this body 7. After crimping, the wall 17 is shaped into a hemispherical form. As shown on Figures, the dimensions of the cavity 16 and of the aperture delineated by the wall 17 after crimping to let through the stud 6 are such that a multidirectional backlash of this stud 6 with respect to the body 7 is possible.

The threaded rod 12 enables the assembly of an extension piece on the stud 6 by screwing, this extension piece enabling, once the screw 1 placed on the pedicula of a vertebra, to run down and to engage easily the connecting part 3 on this stud 6.

The body 7 comprises a proximal collar 18, intended for abutting against the pedicula of the vertebra. This collar 18 exhibits several radial notches 19, notably four notches at 90° to one another, for holding the body 7 in rotation when clamping the nuts 4 and 5.

The linking rod 2 is cylindrical and exhibits such rigidity as to hold several vertebrae with respect to one another. This rod 2 is however deformable in order to be shaped relative to the correction of the rachis to be performed.

The connecting part 3 comprises a rounded section 20 intended for hugging the linking rod 2 and two parallel lateral branches 21, 22.

The distal branch 21 is drilled with a hole for engaging the part 3 on the stud 6, this hole being extended, on its proximal side, by a conical pan 24 adapted to a conical portion of the nut 4.

The distal branch 21 exhibits moreover a hemispherical distal cavity 25, coaxial to said hole and of diameter greater than that of the wall 17. There exists thus a clearance between this wall 17 and the wall of the part 3 delineating the cavity 25, this clearance enabling angular orientation of the stud 6 with respect to the body 7.

At its free end, the distal branch 21 exhibits a proximal boss 26 against which the nut 5 rests when clamped, as shown on FIG. 4.

The proximal branch 22 is shorter than the distal branch 21 and comprises a scalloping 27 at its free end. As shown on FIGS. 2 and 3, this scalloping 27 has dimensions greater than those of the nut 4, to enable this nut 4 to engage into the pan 24 when being clamped, and to clamp this branch 21 against the wall 17 until the connecting part 3 is locked with respect to the stud 6 and immobilisation of this stud 6 with respect to the body 7. The scalloping 27 has moreover dimensions smaller than those of the nut 5, to enable this nut, during clamping, as shown on FIG. 4, to rest against the proximal branch 22 until abutting against the boss 26; this nut 5 thus enables to bring both branches 21, 22 closer to one another in order to immobilise the linking rod 2 in said rounded section 20 of the connecting part 3.

The nut 4 comprises proximal cavities provided around its axis, in order to be driven into rotation, for the clamping thereof, and the nut 5 is a hexagonal flat nut.

In practice, the number of screws 1 necessary to the treatment to be performed is placed in the pediculae of the vertebrae affected, then the extension pieces are screwed on the rods 12. The connecting parts 3, without the rod(s) 2 engaged in their rounded portions 20, and the nuts 4 and 5 are then engaged on these extension pieces and run down along the latter until the parts 3 rest on the walls 17.

The nuts 4 are then clamped in order to clamp the connecting parts 3 against the walls 17 and therefore immobilise these parts 3 and the studs 6 with respect to the body 7.

The rod(s) 2 are then shaped adequately relative to the vertebral correction to be performed, while taking into account the specific position of the parts 3, then this(these) rod(s) 2 are engaged through the portions 20 and the nuts 5 are clamped.

After retraction of the extension pieces, the studs 6 are cut off at tapered zones 15.

FIGS. 5 and 6 show a connecting part 3 and two nuts 4, 5 according to the second embodiment.

In such a case, the nut 4 exhibits a circular external shape and has an external diameter smaller than that of the hole 27 of the proximal branch 22, which enables consequently the nut 4 to run therethrough, without this nut 4 resting against the branch 22.

The distal branch 21 comprises a hole of diameter smaller than that of the nut 4, so that this nut 4 rests, when screwed on the stud 6, solely against this distal branch 21.

The nut 5 also exhibits a circular external form and has a diameter greater than that of the hole 27, so that it rests against the branch 22 when clamped around the stud 6. It therefore clamps both branches 21, 22 and immobilises the linking rod 2.

For their rotational manoeuvres, the nuts 4 and 5 each comprise four radial notches 30, which can accommodate the complementary teeth of a screwing tool.

FIGS. 7 and 8 show a connecting part 3, a nut 4 and a screw 5 according to the third embodiment.

In such a case, the distal branch 21 exhibits a tapered bore 31 for screwing the screw 5 and the proximal branch 22 exhibits a hole of diameter greater than the threaded body of this screw 5 but smaller than the diameter of the head of this screw 5.

The nut 4 has an external form as a portion of a sphere and comprises notches 30 for its rotational manoeuvre.

The screw 5 exhibits a threaded body for screwing in the tapered bore 31 and a circular screw head resting against the proximal branch 22. This head comprises four notches 30 and a cavity 32 as a portion of a hollow sphere, intended for accommodating the nut 4.

The screw 5 is tubular and exhibits an axial bore of diameter greater than that of the stud 6, so that the connecting part 3 may, when it includes the screw 5, be engaged on this stud 6.

Thanks to the screw 5, the connecting part 3 may be clamped on the linking rod 2 then be engaged on the stud 6 and be clamped on the anchoring member 1 using the nut 4.

FIG. 9 shows an embodiment in which the nut 4 has a threaded upper portion on which can be screwed the nut 5.

As shown by the foregoing, the invention provides vertebral osteosynthesis equipment noticeably easier and quicker to implant than any extent equipment, enabling to facilitate significantly the determination of the form to confer the linking rod(s) and enabling perfect clamping of a linking rod, as well as to resist the repeated loads inflected to this type of equipment.

It is obvious that the invention is not limited to the embodiment described above for exemplification purposes but that it extends to all the embodiments covered by the claims appended therein. 

1. Vertebral osteosynthesis equipment, including bony anchoring members, such as pedicular screws (1) and/or hooks, one or two linking rods (2), intended to be connected to these anchoring members and to be attached to the vertebrae by dint thereof, and parts (3) for connecting this(these) linking rod(s) (2) to these anchoring members, at least one anchoring member including a proximal threaded stud (6) and a clamping means (4) for assembling a connecting part (3) thereon, and this connecting part (3) including a clamping means (5) for immobilising the linking rod (2) with respect thereto; equipment characterized in that: said connecting part (3) comprises a rounded section (20) intended for hugging a linking rod (2) and two parallel branches (21, 22) drilled with holes enabling engagement on the proximal threaded stud (6) of said anchoring member (1), these two branches (21, 22) being laid out for being clamped in order to clamp said rounded section (20) around the linking rod (2); and said clamping means (4, 5) may be engaged coaxially on the proximal threaded stud (6) of said anchoring member (1), a first clamping means (4) enabling the assembly of the connecting part (3) on this proximal threaded stud (6) and the second clamping means (5) enabling to clamp both branches (21, 22) of this connecting part (3).
 2. Vertebral osteosynthesis equipment according to claim 1, characterized in that: the proximal branch (22) of the connecting part (3), i.e. the furthermost from the vertebrae after implantation, comprises a hole (27) for letting said first clamping means (4) therethrough, so that said first clamping means (4) rests, when screwed on said proximal threaded stud (6), solely on the distal branch (21) of the connecting part (3), and said second clamping means (5) exhibits a diameter greater than that of this hole (27), so that said second clamping means (5) rests, when screwed on said proximal threaded stud (6), on the proximal branch (22) of the connecting part (3), thereby clamping both branches (21, 22) and therefore immobilising the linking rod (2).
 3. Vertebral osteosynthesis equipment according to claim 1, characterized in that: the hole (31) of the distal branch (21) of the connecting part (3), i.e. the closest of the vertebrae after implantation, is tapered; said second clamping means (5) is in the form of a tubular screw, which may be screwed in the hole (31) of the distal branch (21) and rest against the proximal branch (22) for clamping both branches (21, 22), the axial bore of this screw having a diameter greater than that of the proximal threaded stud (6) so as not to oppose the engagement of the connecting part (3), thus equipped with said second clamping means (5), on the proximal threaded stud (6), and said first clamping means (4) is in the form of a nut which may rest against the head of the screw formed by said second clamping means (5), for assembly of the connecting part (3) on the proximal threaded stud (6).
 4. Vertebral osteosynthesis equipment according to claim 1, characterized in that: the proximal branch (22) of the connecting part (3) is shorter than the distal branch (21) and comprises a scalloping (27) at of its free end; the first and second clamping means comprise nuts (4, 5) which may be screwed on the proximal stud (6) of the corresponding anchoring member (1), said scalloping (27) having dimensions greater than that the nut (4) which is part of said first clamping means, to enable this nut to rest, when being clamped, against the distal branch (21) and to clamp this branch (21) against the proximal zone (17) of the portion (7) of the anchoring member engaged with the vertebra until the connecting part (3) is locked with respect to said proximal stud (6), and said scalloping (27) having dimensions smaller than those of the nut (5) which is part of said seconds clamping means, to enable this nut to rest, when being clamped, against the proximal branch (22) and to bring both branches (21, 22) closer to one another in order to immobilise the linking rod (2) in said rounded section (20) of the connecting part (3).
 5. Vertebral osteosynthesis equipment according to claim 1, characterized in that the proximal zone of the portion (7) of the anchoring member (1) engaged with the vertebra comprises a hemispherical wall (17) and in that the distal branch (21) exhibits a hemispherical distal cavity (25) coaxial to said hole and of diameter greater than that of the wall
 17. 6. Vertebral osteosynthesis equipment according to claim 1, characterized in that the proximal stud (6) exhibits a threaded proximal rod (12) which enables the assembly of an extension piece.
 7. Vertebral osteosynthesis equipment according to claim 1, characterized in that the proximal stud (6) exhibits a threaded cylindrical portion (10) which exhibits a zone (15) of reduced diameter, enabling to break the proximal portion of said threaded cylindrical portion (10).
 8. Vertebral osteosynthesis equipment according to claim 1, characterized in that the nut (4) has a threaded upper portion on which can be screwed the nut (5). 